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[ballastanksian]

I like the water catchment idea. I plan to do similar on the Novgorod when I get to it to surround the motors and electrical gubbins in their waterproof box.

I recall you having buzzers to indicate critical waterlevel in Poly, so you could do the same to insure Agincourt's safety.

[C-3PO]

Hi Bob,

Good to see you are making good progress with your build which makes fascinating reading....

Regarding your water pump direction control and water ballast level requirements:

This could be very simply and cheaply achieved with a standalone (separate to gun turrets) Arduino and relay board. ( total cost less than £10)

This would give you the following functionality

- Water level sensor - could switch off pump/sound an alarm or both when preset water ballast level reached - sensor would simply be 2 wire probes - one stuck to the hull at your required water level
- Switch pumps on/off and control flow direction using a small relay board to accomplish power reversal to pump motor with an inbuilt safety relay to ensure shorting would not occur

The switching could be done from one channel on your radio and could be made "intelligent" ie. - if water can be sensed in hull then pump out - if water can't be sensed then pump water in

Regards
C-3PO

[Bob K]

Hi C-3PO.    Ingenious (and Arduino based of course, knowing you).   At this rate I could end up with enough Arduino's on board to have to take their weight into account -  Tee hee 
Obviously one system per hull half, no interconnecting wiring between hulls.

I am still looking for a bidirectional / reversing 12V pump, capable of a reasonable flow rate.
A bidirectional pump would be the simplest solution.
The wire sensors sound similar to the principle used in Hunter Systems ballast pump controller.

I reckon that if I have a sealed-in tank between two bulkheads I can just about get the 5kg per hull half required.
ie 2 x 5 litres. 

[C-3PO]

Bob the Arduino needed to control this would only weigh 6g

I think finding a reversible pump might be a challenge - I wonder if you could use 2 of these in each hull half.

http://www.ebay.co.uk/itm/12V-DC-5W-Micro-Mini-Ultra-quiet-Brushless-Water-Pump-Oil-Car-Submersible-0-75-/142391493307?epid=574889495&hash=item212731c2bb:g:5JcAAOSwGJlZI76u

It might work  to have just a single inlet/outlet through the hull - if the pipe connected to the hull was connected to pump 1, the outlet of pump 1 connect to the outlet of pump 2 ( the opposite way round)

As only one pump would be working at any one time the water would hopefully just flow through the other inactive pump - not sure I have explained this well - maybe a simply diagram might help

Regards
C-3PO

[Bob K]

Thanks for the info on those pumps C-3PO, four are on order.

Apart from that everything is on hold.  Now I've got the brass bar, drills and other bits, then my Bosch drill decides to pack up       It cut out a couple of times, then refused to run.  Looking up on YouTube I suspect the brushes may be past their Sell By Date.  Ordered some on EBay, but turns out they're coming from Luxembourg so could be up to three weeks.
So, no drilling.  It may be that will not fix it.  If so it will be hard to replace the drill like-for-like.  Obviously it must be cordless, with the standard collar for my new pillar drill stand, and a proper chuck with key.  Rare beasts nowadays.
Most look like sub machine guns with a huge weight under the stock.  Useless !

So the workbench has a partially dismantled Bosch drill and the shipwrights have been laid off.

[ballastanksian]

I cannot see how building the Agincourt could have upset the Model boat building spirits enough to cause you drill angst? I am trying to think of what you could do to assuage them Bob 

It is typical that you have just got the stand that fits that drill. GRRR 

[Bob K]

Mini Shipwrights re-hired

Quicker than I expected, the replacement brushes for my 25-year-old Bosch drill arrived.  A bit of a fiddle but thanks to a YouTube demo I have them fitted and the drill now runs like new.  The mini shipwrights are re-hired and work can resume.

With my pillar drill working again I drilled the square brass bar for the 4 inch tie-bar, then drilled and shaped the latch end. 



Next was dowel-securing the two double bulkheads together, drilling and chiselling out a long square hole through both for the brass latch.  Hurrah for the pillar drill stand to keep the chain-drilled holes square through almost 40 mm of plywood.  The fixed end of the latch will be epoxied in that bulkhead.



Plumbing

Looking ahead, the four mini pumps recommended by C-3PO were tested and were easily able to lift water to at least 500 mm at a good rate.  I intend fitting in-line filters to prevent the ingress of pond weed and debris.  I am working on diagrams for siting and plumbing.  In each half, one to pump in and one to pump out.  I will probably opt for float switches.  The pumps will operate from one Rx channel via a cam with two microswitches, similar to my HMS Polyphemus.  Keeps it simple.  Inlet and outlet pipes, ¼ inch bore, through the hull just below “dry launched” waterline, inside the ballast chambers.

[ballastanksian]

You're cruising now Bob  There are lots of ideas to store away for future use.

[Bob K]

Bulkhead fixing

After completing the latch mounting, plus other woodworking mods before it all gets fixed in position, the next stage was to secure the bulkheads in the hull.  The interfacing bulkheads were epoxied in first, flush with the cut edges.

Then I needed to fix the ends of the 25mm tubes into the two double bulkheads, as they need to be just under-proud of the interfacing join.  Insert some Araldite into the holes, slide into position, then slide up the O ring on the hull face.  That should ensure the outer tubes stay put.

Each of the inner bulkheads were marked out on inside of the the hull, a coat of Araldite applied between the marked lines, then slid into place.  Squareness etc checked, and clamps applied.  Only 5 mins working time for each operation



Note that the O rings for the other bulkhead tubes are positioned ready for hole sealing for which the half-hull assemblies will each be placed on end.  The hull joints will be filleted with Isopon P40, dowel holes filled, and all sealed internally with fibreglass resin.

All coming all along well I think.

Ballasting

The outermost pairs of bulkheads will be used for water ballasting, to the same depth as the exterior waterline.
That works out to 9.9 Kg of water, almost spot on what I need.

[Bob K]

P40 Disaster

A snag.  Trying to use Isopon P40 was a total disaster.  A large proportion of the five minutes “use” time is consumed by thorough mixing.  After that it refuses to be picked as a workable ball, making a total mess of everything in the vicinity, and forcing you to use fingers to apply it to inside corners.  Worst of all it is impossible to create any kind of fillet as would be easy with P38 filler which I have used before.

Up to this point I have used Alaldite and Z-Poxy without problem, keeping everything neat and tidy.  I have now even got P40 over the previously pristine stainless tubes.
Ah well, that’s one consigned to experience, and the bin.  I will revert to either P38 or Plastic Padding, reinforcing later with resin and f/g cloth.

[Bob K]

After having found that P40 is totally useless for forming strong supporting fillet radii on inside corner / edges I tried P38 instead.  Tried it on a test piece.  Far too runny to create any kind of decent internal radii.  It used to be "thicker" than that.

What I guess I need is something more like an epoxy "soft putty", something I can press well into the corner edges then smooth to form approx. 10mm radii, and not in 40 gm packs (I would need dozens).

Ideas ?

[tugboat Tom]

Bob
I have used a epoxy that is thick enough that it wil not drop down.
https://www.polyservice.nl/Poly-Pox-Lijm-700-200-gr-pasteuze-epoxyhars-p-16188.html

[Colin Bishop]

Bob,

You might find that Ronseal High Performance Wood Filler would do the trick.

http://www.ronseal.co.uk/home/fillers/high-performance-wood-filler/

It comes in white or natural (light beige). I find it better to work with than P38 (not so runny if you stir it up a bit first) and it sands down very easily but you would need to try it. It will stick to wood and GRP OK.

Colin

[Geoff]

In the past I have just used slow set epoxy glue to fix the bulkheads then a small fillet of plastic padding (wood filler may not grip) smeared in with the finger. Once set I have used a larger fillet of fibreglass repair paste to really fix the bulkhead. It is important to rough up the hull surface very thoroughly to the point some of the fibres are showing.

Good luck

Geoff

[SailorGreg]

Well, the way it is done on full size boats is to mix some epoxy and thicken it with one of the several fillers available.  Filleting joints is a common way of joining panels and putting bulkheads into boats these days and is plenty strong.  Car body filler isn't really designed to be used on a structural load bearing joint, although on most of our models it is entirely adequate.  However, when we get to a model the size and weight of Agincourt perhaps a look at full size practice might help.

There are plenty of Youtube clips showing how to do filleting, some more detailed than others.  Search "epoxy filleting".  As for thickening the epoxy (Z-poxy should work fine here), there is a big range of fillers to give different characteristics to the epoxy, but all you really need is West's filleting mixture - that tub should keep you going for a while!  A little practice never goes amiss (as I have proved on many occasions ) but neat fillets are actually quite easy and make the inside of the boat look nice and clean.  Everyone talks about "peanut butter" consistency for the mixture and I have found you need a fair bit of the filler to get to that stage, but once you are there the mixture is easily worked.

Good luck and have fun.

Greg

[radiojoe]

Surprised that the P38 was too runny, it's what I always use, mixing just enough to do a section of a bulkhead at a time, applied with the shank end of a drill to form the radii, and trimming of the waste as it sets, applying with drills give you a selection of sizes, and when you try removing a bit of waste that has set you realise just how well it bonds.


Joe

[Ian K]

Hi Bob,

P40 does work well for fillets, for me at least there is a knack to it. Mix it in smaller quantities, using slightly less catalyst.

Buy some disposable nitrile gloves and pick some of the mix, up on a suitable gloved finger and simply run your mix around the area to be bonded. Before the mixed P40 starts to set dip a clean gloved finger into a dish of water and smooth off the surface.

See attached pics as proof of success, for me.

Regards

Ian

[Bob K]

Thanks guys.  Some good food for thought there.

Sailergreg:  You are right about the size of Agincourt, it feels more like working on a real boat.

Ian:  There is no way I could get P40 to do that, it's just a messy smear - over everything.

What really gets in the way is the forest of one inch stainless tubing going through the whole lot.  If they were not there I could probably make up some kind of filleting tool, but this is going to have to be a finger application job, doing a little bit at a time.   Hence something more like the "feel" of Milliput as a putty.

PS:  The Z-Poxy was ideal consistency for sealing the tube holes, and the O rings were perfect for the job.

[steve pickstock]

What about an epoxy putty like Milliput?

[ballastanksian]

A couple of boxes would do the trick.

Was your filler in a tube or tub Bob? If the former, you may have got runnier consistency coming out first with thicker consistency later. I have found this happen before and helps you not one iota.

Onwards and upwards 

[Bob K]

Ian:  I would probably need at least six boxes with the size of these bulkheads.  Yes, the runny P38 was in a 120 ml tubes.  I had used a big tin before.  Maybe that was the difference.

Experimenting

I had thought of using ‘standard’ Milliput, which is epoxy, but one pack will probably only be enough to do both sides of one bulkhead so I would need another five packs.  I could do a small section at a time, working around this forest of stainless tubing is challenging.   A few sculpting tools need to be made for the radii. 

A pity about the P38 which turned out to be far more runny than I’d remembered.  I need something a lot stiffer to sculpt with.

I will try a section with Milliput.  It can’t be worse than the P40.  If that works I will have to buy in a large stock from Amazon.  It will be worth if it does a secure neat job.

[Colin Bishop]

Milliput seems an expensive way to go. There are various marine or plumbers epoxy putties which come in a two part stick that you knead before use and which can be smoothed out with a wet finger and which would be rather more economical to buy. They are very effective, I used them when I had a 1:1 scale boat. They are advertised as setting underwater!

Colin

[steve pickstock]

If you do use Miliput I would still paint resin over the join as it does shrink slightly when dry (it's a very tiny shrinkage).

[Bob K]

Experimenting

First, the result of using P40.  Like trying to sculpt with blancmange.  Messy and ineffective.



Experimenting

Next I tried ‘standard’ Milliput, which is epoxy, but one pack was only just enough to do both sides of one bulkhead with radii so I will need another five packs.  I did a small section at a time, working around this forest of stainless tubing is really tough.  No  sculpting tools needed.  I lightly wetted the surfaces, applied a small ‘sausage’, then formed it in place with a wet finger.  It seems just the job, so have ordered a five pack from Amazon.  £10.70 for five with free UK delivery.  That is about AUS$17.85 Colin.



That’s more like what I wanted.  Six packs cost far less than either the big P40 or 3 x P38 tubes that both proved useless. 

Steve:  Yes, the intention is to apply fibreglass resin afterwards, with lightweight laminating fabric, but I need a good fillet first.  I can mix and apply with a small brush.  Together with the initial Araldite bond, then Milliput, the resin and cloth should make a really strong support.

[JimG]

A bit more expensive way would be to use Hysol (Loctite 9462) as used by the jet flyers to add fillets to wood formers in glass fuselages. It is a thixotropic epoxy which means it stays where it is put and doesn't run. You do need the applicator gun which uses a mixing tube to give the correct proportions and mixes the two parts ready for use.
http://www.motorsandrotors.co/index.php?main_page=index&cPath=79&zenid=cq5u9enqnf7qoaor8k2l89e2m2

Jim